The present invention relates to fiber optic circuits and modules for fiber optic equipment.
The telecommunications and data transmission industries are rapidly expanding their development of fiber optic transmission systems. Historically, telecommunications signals and data have been transmitted over wire lines such as twisted pair or coaxial cables. In order to accommodate higher signal rate speeds, the industry is turning to increased use of fiber optic cables as the transmission medium.
As the use of fiber optic cables increases, the need for peripheral equipment has increased. For example, it is desirable to have access to a fiber optic line for the purpose of either re-routing the line in the event of damage to the line or to have access to the line for the purposes of monitoring or testing the line.
Fiber optic peripheral equipment for cable management, cable storage, and connection capabilities are well known. The use of modular fiber optic connector modules is known for performing so-called cross-connect applications. U.S. Pat. Nos. 5,432,875 and 5,363,465 to ADC Telecommunications, Inc. concern fiber optic connector modules and chassis designs for receiving the modules in cross-connect applications.
There is a continuing need for fiber optic circuits and systems which provide optical signal routing, monitoring, and access capabilities.
The present invention includes an optical circuit for connecting fiber optic cables and/or equipment, including one or more switches in the optical circuit for changing the optical signal paths of the circuit. The switch or switches can be used to selectively link the optical signal paths to access terminals, such as for signal testing, monitoring or re-routing. The optical circuit may allow for one or more of the following functions for signals passing through the circuit: passing through of the signals, non-intrusive monitoring of the signals, looping back of the signals between the transmit and receive terminals, and splitting of the signals, such as in combination with test equipment.
One circuit of the present invention includes two optical signal pathways and a switch between the two signal pathways allowing normal pass through of the signals along each signal pathway in one state, and looping back of the signals in a second state. Access to one or both of the signal pathways can be provided to the circuit by non-intrusive monitors, or switches, such as 1xc3x972 switches or 2xc3x972 switches.
Remote control of the one or more switches in the optical circuits of the present invention allows for remote test access, in one preferred system.
The optical circuits of the present invention can be housed in one or more housings, as desired. Modular housings allow for convenient assembly, use and maintenance of the system.
In accordance with the invention, one preferred embodiment includes one or more fiber optic modules which are mountable to a chassis for holding one or more modules. Each module may have a plurality of connection locations for coupling to fiber optic connectors. The connection locations are linked together by optical couplers within the module. Telecommunications cables and equipment are connected to first sets of the connection locations of the modules. The modules may be used to cross-connect fiber optic equipment via patch cords between second sets of the connection locations, or the second sets of the connection locations may be connected together within a single module.
One preferred embodiment of the fiber optic module of the present invention includes a first pair of adapters for connection to fiber optic connectors and a second pair of adapters for connection to further fiber optic connectors. The first and second pairs of adapters are connected by fiber optic signal pathways through the module. One adapter of each pair may define a transmit signal port, and the other adapter of each pair may define a receive signal port. The first pair of adapters may be connected to a cable entering a customer""s facility. The second pair of adapters may be cross-connected to another module at the customer""s facility, or the adapters may be connected to other fiber optic equipment.
One preferred embodiment of the fiber optic module includes a first switch between the first and second signal pathways wherein both pathways are in a straight pass through configuration when the switch is in a first state, and wherein both pathways are linked to form two loop back pathways through the module when the switch is in a second state. One preferred embodiment includes a 2xc3x972 optical switch.
One further preferred embodiment of a fiber optic module includes a third pair of adapters, such as for use in connecting to test or access equipment. A second switch links the third pair of adapters to either the transmit signal pathway or the receive signal pathway. The second switch has at least two states, wherein a first state of the second switch optically links one adapter of the third pair to the other adapter of the third pair in a loop back configuration. A second state of the second switch optically links one adapter of the third pair of adapters to one of the adapters of the first pair, and the other adapter of the third pair is optically linked to the first switch. Splitters and monitor ports may be linked to the transmit and receive signal pathways in preferred embodiments.
In an alternative preferred embodiment, a single additional adapter may be provided, instead of the third pair of adapters, and a single 1xc3x972 optical switch provided in either the transmit or receive signal pathways. The 1xc3x972 switch optically isolates the third adapter in one state, and optically links the additional adapter to the first switch when the 1xc3x972 switch is in a second state. Splitters and monitor ports may be linked to the transmit and receive signal pathways in preferred embodiments.
Further embodiments of the invention include an optical circuit including first and second pairs of connection locations, each pair defining a transmit signal connection location and a receive signal connection location. The transmit signal connection location of each pair is optically linkable through a signal path to the receive signal connection location of the other pair. One or more access connection locations are provided which are linkable to one of the signal paths through the circuit. One or more switches may be provided to selectively link the access connection location(s) to one of the signal paths. A first switch, such as a 2xc3x972 switch, between the signal paths, and a second switch, such as a 1xc3x972 or a 2xc3x972 switch between one of the signal paths and the access connection location(s) are provided. The first and second pairs of connection locations defining the transmit and receive signal connection locations may be part of a single module or housing construction in a frame, rack or chassis, or they may be part of separate modules or housing constructions cross-connected together through optical signal pathways, such as patch cords or other optical links.
The circuits of the present invention may be used in a variety of applications, such as for looping back of signals, or for splitting signals in combination with test equipment.